The cyclopentenedione, 2,2,4-trimethyl-cyclopent-4-ene-1,3-dione is a known compound having olfactory properties and useful as an intermediate in various systems. Hitherto, the aforementioned cyclopentenedione was accessible only in a complicated manner, for example via 3,3-dimethyl-bicyclo [3.1.0.] hexanedione (2,4), and in low yields.